This invention relates to a rubber-covered cord units joining machine in which a number of parallelogram-shaped rubber-covered cord units are joined to one another by overlapping their edges which are in parallel with the cords thereof to form a belt-shaped rubber covered cord product which is used, for instance, for manufacturing ply-cords for automobile tires. The parallelogram-shaped rubber-covered cord units are formed as follows: A number of fiber or steel cords arranged parallel with one another are covered with rubber to form a rubber-covered cord assembly, and the rubber-covered cord assembly thus formed is cut perpendicularly or obliquely to the cords thereof, to form the aforementioned parallelogram-shaped rubber-covered cord units.
Japanese Patent Application (OPI) No. 11236/1984 has disclosed a rubber-covered cord units joining machine. In the machine, a first conveying mechanism for conveying a joined rubber-covered cord unit in the lengthwise direction and a second conveying mechanism for conveying a rubber-covered cord unit to be joined (hereinafter referred to as "a not-joined rubber-covered cord unit", when applicable) towards the rear end of the joined rubber-covered cord unit are arranged in series, a first shaping mechanism is protruded in the conveying surface between the first and second conveying mechanisms from below so that the rear end of the joined rubber-covered cord unit on the first conveying mechanism is pushed forwardly with the substantially vertical shaping surface of the front portion of the first conveying mechanism, to shape the rear end, the front end of the not-joined rubber-covered cord unit is caused to ride on the ride-on surface of the upper portion of the first shaping mechanism which is inclined upwardly, the front end is pushed backwardly by a second shaping mechanism moving downwardly to make the front end parallel with the rear end of the joined rubber-covered cord unit, and thereafter the first shaping mechanism is moved downwardly to lay the front end of the not-joined rubber-covered cord unit over the rear end of the joined rubber-covered cord unit, and the front end and the rear end are joined together under pressure.
In the above-described conventional joining machine, the rear end of the joined rubber-covered cord unit is pushed forwardly by the first shaping mechanism while the front end of the not-joined rubber-covered cord unit is pushed backwardly by the second shaping mechanism so that the rear end is made parallel with the front end and at the same time the front end is laid over the rear end for joining them together. Therefore, the rubber-covered cord units are partially curved upwardly by the pushing operation. If the front end and the rear ends are pushed greatly, then the cord units overlapped are creased by pressing. If, on the other hand, the front end and the rear end are not sufficiently pushed, then the front end of the not-joined rubber-covered cord unit or the rear end of the joined rubber-cover cord unit are pushed back by the elasticity of the upwardly curved part after the first and second shaping mechanisms have been retracted, with the result that the degree of parallelism is lowered or the not-joined rubber-covered cord unit and the joined rubber-covered cord unit are excessively overlapped. Furthermore, in the above-described conventional joining machine, the degree of parallelism and the amount of overlapping of the rear end of the joined rubber-covered cord unit and the not-joined rubber-covered cord unit are controlled; however, the positions of the rear end and the front end in the widthwise direction are not controlled. Therefore, in the case where the joined rubber-covered cord unit and the not-joined rubber-covered cord unit are shifted in the widthwise direction from each other or they are different in width from each other, steps different in length are formed on both sides of the joint line or a step is formed on one side of the joint line. In the conventional joining machine, the front end of the not-joined rubber-covered cord unit and the rear end of the joined rubber-covered cord unit are pushed as was described above. Therefore, in the case where the joining machine is used to join rubber-covered cord units for radial tires which are formed by cutting the rubber-covered cord assembly obliquely with respect to the direction of the cords, the cord units must be constant in the angle of inclination; that is, the joining machine cannot be used for a variety of rubber-covered cord units different in the angle of inclination with respect to the direction of the cords.